Rubbery butadiene-styrene copolymenr compounded with an acid soluble hydrocarbon oil



Patented Sept. 26, 1950 UNITED STATES PATENT OFFICE RUBBERY BUTADIENE-STYRENE COPOLY- MER COMPOUNDED WITH AN ACID SOLU- BLE HYDROCARBON OIL Lawrence R. Sperberg, Phillips, Tex., and Chester 0. Crawford, Bartlesville, kla., assignors to Phillips Petroleum Company, a corporation of Delaware No Drawing. Application January 5, 1948, Serial No. 648

1 4 Claims. (Cl. 260--33.6)

This invention relates to rubber materials. In shrinkage. Various known agents are used to aid one aspect this invention relates to compositions milling by virtue of their affinity for the rubber of natural rubber, reclaimed rubber, and natural material and are referred to hereafter as rubber rubber substitutes or synthetic elastomers, in plasticizers or softeners. Plasticizers or softenwhich plasticizers or softeners have been incor- 5 ers when incorporated with rubber-like materials porated. In a more pecific aspect this invention serve to increase the pliability, durability and tack is related to the utilization of acid soluble oils of the composition as well as to facilitate comobtained as a by-product from a hydrocarbon pounding, both by aiding the dispersion of solids conversion process wherein an inorganic acid such and by lubricating the mix, whereby less power is as hydrofluoric acid comprises the catalyst. consumed in the mixing, and prevulcanization is In the processing of rubber, herein comprising greatly minimized. Many of the types of softennatural rubber, reclaimed rubber, and synthetic ers used are vegetable and mineral oils, waxes, elastomcrs of the types comprising polymers of asphalts, rosin, and tars. The various softeners ut i e. a y h p en b t function is different capacities but generally are diene-acrylonitrile, etc, as described more fully of a s l ent, swelling, or lubricating type and are hereinafter, it is necessary to compound or mix dd d on the mill, thereby conditioning said said rubber with certain ingredients which accenber material for mixing or compounding as aforetuate certain characteristics for the use intended. described The effectivenes of t various fsuch ingrdlents are, for example, i teners differs greatly and the proportions in which able reinforcing pigments as carbon black, zmc 2o they are added vary. The addition of softeners Oxlde, or magnesium carbonate, Var 1011s accelera' to rubber stocks modifies the properties of the final tors, sulfur, etc, andare a o those Whmh in vulcanizate considerably. In order to carry out various combmatlotls lmpart lmprovedrmpertles the processing satisfactorily, large quantities of to the fi vulczfutlzate as sald softeners are oftentimes necessary. This is espeprppertlfgs compnsmg abrasion hyster cially true in the procesing of rubber substitutes resistance to tear tensue :Strength elonga' or synthetic elastomers, wherein milling presents antimodulus added difiiculties, since the oxidative breakdown Raw lubber stocks ale tough and non-plasma which occurs in the plasticizing of natural rubber and must be softened or rendered in a plastic condition to readily absorb the compounding indoes not occur to the Same degree m the process ing of high molecular weight synthetic rubbers gredients aforedescribed. Mixing of tough rubber stocks with compounding ingredients is ef- :rhlch 1 fzequentlg tonal} and il to fected by means ofmastication or softening at a n mos ms ances .epen upon e W controlled temperature the range of m R present and the efficiency of different plasticizei s,

Mastication involves mechanically kneading the 3: physlcal propertles are degraded by.the rubber materia1 ither by passing it through' addition of softener, to the rubber mlx, especially open mill, i. e. passing it between rollers running large a of softeiler i resultltlg at different Speeds whereby it is Subjected to in the lowering of the abras on resistance, tensile pression followed by a shearing action, or by placstrength and other propertles' ing it in an enclosed mixer of the Banbury type 40 W have novel softeners where much the same fi t is predated. The their incorporation with rubber stocks, provide Open mm and the Banbury type mixer comprise rubber compositions of desired plasticity and tack standard equipment used in compounding on the mill and which as regards stress-strain Mastication or softening referred to hereinafter D D f and high abrasion resistance provide as milling, is time consuming, requires power and for Superior rubber Productsliberates great heat to a damaging extent. Con- This invention has as an object to p o de nove sequent excessive temperatures during the milling u e plast c sof the rubber material are undesirable since they Another object of this invention is to provide usually lead to prevulcanization or scorching, difrubber co p especially Suited for tire ficulty of maintaining uniform thickness in caltread stocks and for applications requiring a high endered or extruded mixtures, and to excessive degree of reinforcement.

A further object of this invention is to provide rubber compositions and novel plasticizers incorporated therein, the novel plasticizers comprising acid soluble oils or fractions thereof, obtained as a by-product of a hydrocarbon conversion wherein an inorganic acid such as hydrofluoric acid comprises the catalyst.

Still a further object of this invention is to provide a method of plasticizing or softening natural rubber or synthetic elastomers.

Other objects and advantages of this invention will become apparent to one skilled in the art from the accompanying disclosure and discussion.

The novel effective softeners of our invention are the acid soluble oils, or a fraction or fractions thereof, said acid soluble oils being obtained from a hydrocarbon conversion process wherein an inorganic acid such as hydrofluoric acid comprises the catalyst, and which is more fully described hereinafter.

In the conversion of certain hydrocarbons in the presence of a catalyst comprising hydrofluoric acid, acid soluble oils are formed as byproducts and are present in the acid phase. Perhaps one of the most important of such conversion processes in which acid soluble oil are formed is the alkylation of hydrocarbons in the presence of hydrofluoric acid as a catalyst. This so-called hydrofluoric acid alkylation involves reaction of an isoparafiin, particularly isobutane,

or an aromatic hydrocarbon such as benzene, toluene, xylene, and the like, with an alkylative reactant such as propylene, various butyle'nes, amylenes, and olefin mixtures boiling up to 500 F. The reactants are contacted at temperatures in the range of JO-150 F. and under suflicient pressure to maintain the reactants in liquid phase with liquid concentrated hydrofluoric acid for a reaction period ranging from about 145 minutes. The reaction efiluent is passed to a settling zone wherein the liquid hydrocarbon-rich phase and the heavier liquid hydrofluoric acidrich phase are separated.

The hydrofluoric acid catalyst initially anhydrous and having an HF content in th range of 95-99 per cent gradually becomes contaminated with such impurities as water, organic fluorine compounds, heavy oils, etc., which stay in solution in the acid. When the hydrofluoric acid content, or acidity, of the acid phase becomes as low as about '75 Per cent by weight, under-reacting as a result of reduced catalyst activity is en-- countered and the acidity must be restored to and maintained at values higher than 75 weight per cent, usually in the range of 85-90 weight per cent. The acidity of the catalyst is usually maintained in the range of 80-90 per cent by passing the acid phase or a portion thereof to a purification means or an acid rerun unit wherein the impurities, including the acid soluble oils of our invention, are removed and the purified hydrofluoric acid returned to the active catalyst in the hydrofluoric acid conversion process. The acid phase contains in addition to the impurities above mentioned, physically dissolved minor amounts of hydrocarbon reactants which may be separated by an extraction means employing a heavy fraction of the finalproduct of the conversion process as an extracting agent. For example, in a hydrofluoric acid alkylation process, heavy alkylate may serve as the extraction agent. The acid layer subsequent to the extraction, abovedescribed, is heated to a temperature in the range of 250-300 F. and then flashed in a bafiled tower wherein the free acid and water are vaporized and passed overhead and the soluble oils and other heavy materials, not vaporized, descend into a packed acid-oil fractionator. The fractionator kettle is operated at temperatures approximating 400 F. and higher, and provides therein a means of vaporizing any free hydrofluoric acid and/or water remaining in solution with the said heavy materials and of decomposing the organic fluorine compounds therein. The free HF, water, and decomposed compounds aforesaid are passed overhead. The bottom prodnot of the said fractionator comprises the acid soluble oils of our invention, is substantially free of water and fluorine-containing compounds, and of traces of hydrofluoric acid, boils mostly in the gas-oil range, and is partially cyclic. These acid soluble oils occur as by-products of the various hydrocarbon conversion processes employing a catalyst comprising hydrofluoric acid such as, for example, alkylation as aforedescribed, isomerization, wherein normal paraflin or olefin hydrocarbons are converted to more branched type compounds and cyclic hydrocarbons are converted to other higher and lower boiling cyclic compounds, and reforming, wherein normal parafiin hydrocarbons such as normal butane, normal pentane, hexanes, heptanes, etc., are disproportionated to both high and low-boiling iso- First drop 220 5 480 10 546 1 Cracking begins.

When referring herein to a catalyst comprising hydrofluoric acid it is to be understood that not only hydrofluoric acid alone is meant, but any of the various hydrofluoric acid-containing catalysts employed in hydrocarbon conversion processes such as for example, those processes aforesaid. Hydrofluoric acid-containing catalysts herein comprise hydrofluoric acid alone or mixtures of hydrofluoric acid as the chief component with sulfuric acid, boron fluoride, metalloid halides of the type of phosphorous pentafluoride or with other promoters or modifiers, all in minor proportions usually comprising 1-5% by weight of the said mixture although in some instances comprising a proportion as high as 10% by weight or higher. Hydrofluoric acid-containing catalysts comprising mixtures as described above, are employed in a manner substantially the same as that for hydrofluoric acid alone with only minor modifications that will be obvious hydrocarbon conversion process employing a catalyst comprising hydrofluoric acid and vary in composition somewhat, dependent upon such factors as the nature of the hydrocarbon charge stock, the particular hydrocarbon conversion process employed, and the additional component or components of the hydrofluoric acid catalyst, if any are present.

By vacuum distillation of the aforedescribed acid soluble oils, resins varying in physical state from a semi-solid, slightly tacky material to a hard brittle mass may be obtained. We have found that these semi-resinous and resinous poly-. mers, when incorporated as softeners with natural, synthetic, or reclaimed rubber stocks, provide rubber compositions of improved processing characteristics and physical properties, especially as regards tensile strength and abrasion resistance. The properties of the acid soluble oil and the resinous materials prepared therefrom are presented in the following tabulation:

Properties of HF-acz'd soluble oil API gravity 60 F -30 Viscosity SUS 100 F. 100-1000 Viscosit SUS 210 F. 40-80 Flash point, COC, "F. 190-250 Fire point, COC, F. 220-270 Pour point, F. -30-5+ Total solids, per cent 65-80 Iodine number 5 150-300 Aniline point, C. 6 30-100 Free HF None Properties of resins from acid soluble oz'Z Yield, weight per cent of charge -40 Distillation at 10 mm, F. 390-600 Softening point, *F 110-170 Iodine number 155-160 Ash Trace Acidity Less than 0.3.

?A. S. T. M. designation 4-l639.

-\ T. M. designation D9245.

l S. '1. M designation D97.

A T. M. designation D154.

W1js method-gins. iodine/100 g'ms. sample.

S T. M. designation D611--44T. S. T. M. designation D66344T.

S. T. M. designation D36-26.

S T. M. designation D128.

A A A A polymerization or homogeneous polymerization (sometimes called mass polymerization). The elastomers are prepared by polymerization of conjugated. diolefins such as butadiene, isoprene,

piperylene and the like, either alone or in admixture with each other or with other polymerizable organic compounds such as styrene, dichlorostyrene, vinylpyridine, acrylonitrile and the like. In emulsion polymerization, various modifiers, initiators, emulsifying agents, etc. may be employed. In the homogeneous type polymerization, catalysts such as alkali metals and the like ma be employed. The following is a conventional recipe for the emulsion type preparation of a butadiene-styrene copolymer and is that employed in the preparation of the butadiene-styrene elastomer referred to in the examples herein:

Parts by weight Butadiene Styrene 25 Potassium persulfate 0.30 Tert. -C12 mercaptan 0.28 Soap i 5.0 Water rubber.

Stocks from our compositions are especially useful for footwear, tire carcasses and treads and hard rubber mechanical goods, due to their excellent stress-strain properties and high abrasion resistance. tabulation of stress-strain and abrasion properties of eight butadiene-styrene copolymer compositions x in each of which an acid soluble oil or a defined fraction thereof has been incorporated as a softener. The rubber softeners of our invention comprise as high as 50 per cent by weight, and preferably in the range of 3-20 per cent by weight of our compositions.

Advantages of this invention are illustrated by the following examples. The reactants and their proportions and other specific ingredients of the recipes are presented as being typical and should not be construed to limit the invention unduly.

Emample I Carbon black (furnace type) 17 Channel black 35 Zinc oxide 3 -Sulfur -1. 1.75 Accelerator 1 1.07 Softener a 8.00 Condensation product of mercaptobenzothiazole and cyclohexylamine.

The acid soluble oil fractions employed were of the following boiling ranges, F.:

nso Light ASO Heavy 1) 132 to 303 (4) 183 to 370 29s to 4 (5) 356 m 482 70 (3) 470 (Resinous) (6) 482 (Resinous) In Example I is shown a.

Stress-strain and abrasion properties measured A regular production sole stock (factory conat 80 F. were as follows: trol) was evaluated for comparison. Stress- Unaged Oven Aged 24 hrs. 212 F.

Stress p. s. i. g Stress s. i. Abrasion Fmflon Per Cent p Per Cent gms. loss Elongation Elonga. on Miiliomus Tensile at break Mom? Tensile at break 1, 370 2, 460 490 2, 426 2, 620 330 2. 45 l, 190 2, 570 520 2, 220 2, 730 360 2. 79 l, 200 2, 740 570 2, 180 2, 860 400 3. 27 1, 320 2, 650 510 2, 350 2, 990 385 2. 68 1, 200 2, 460 515 2, 170 2, 610 360 3.20 1, 060 2, 350 515 1, 950 2, 720 410 3. 80 1, 250 2, 700 545 2, 290 2, e 345 2. 91 l, 280 2, 740 640 2. 89 1, 195 2, 665 560 2, 005 2, 565 375 3. 53

1 Asphalt.

. All samples exhibited good plasticizing effects of the acid soluble oils and fractions thereof on strain and abrasion properties were measured at 80 F. and are as follows:

the mill. The stress-strain and the abrasion resistance properties show the total acid soluble oil, and the fraction or fractions thereof to be effective plasticizers and to be especially suitable for tire tread and other applications requiring a maximum of reinforcement.

oftentimes, in order to carry out processing satisfactorily and to arrive at a desired degree of quality commensurate with cost, large quantities of softeners are necessary and consequently, in some instances, other qualities of the vulcanizate are impaired thereby. Butadiene-styrene c0- polymer compositions for a soft type shoe sole stock were prepared, as shown in Example II, employing acid soluble oils as softeners in quantities larger than those used in tire tread compositions.

Example II The following soft type shoe sole butadienestyrene copolymer composition was prepared employing acid soluble oil as a softener.

Parts by weight Butadiene-styrene copolymer 100 Soft carbon black 100 Softener '40 Zinc oxide 3 7o Sulfur 2 Accelerator 1 1.2 Accelerator 2 1.2

1 Benzothiazyldisulfide.

An ester of two molecules of diphenyl guanidine and one molecule phthalic acid.

Abrasion tests for the above 75 minute cure samples gave the following results:

Abrasion loss (gms.)

Oven Aged Softener Unagcd 24 hrs.

Acid Soluble Oil. 5. 41 3. 46 ontrol ll. 53 ll. 13

The example demonstrates the utility of the acid soluble oil softener by virtue of the excellent stress-strain and abrasion properties exhibited.

Example III Parts by weight Butadiene-styrene copolymer Furnace type black 75 Softener 10 Zinc oxide 3 Parts by weight Sulfur 1.75 Accelerator 1 1.35 Accelerator 0.225

1 Condensation cyclohexylamme.

Reaction product of butyraldehyde and butylidene aniline.

product of mercaptobenzothiazole and Stress-strain and abrasion properties as follows were measured at the temperatures indi cated in the following table.

Stress, p. s. i.

Minutes Per Cent Abrasion (Eur s Per Cent Elongation Elongation Loss, 320 F. at Break at l3reak gms.

UNAGED, MEASURED 80 F.

5 150 380 420 580 645 680 580 290 630 1, 120 l, 570 l, 890 485 365 1, 000 l, 890 2, 500 2, 810 425 25. 480 1, 420 2, 225 2, 790 2, 800 415 UNAGED, MEASURED 200 F OVEN AGED 24 HRS. 212 F MEASURED 80 F.

Milling characteristics indicated good plasticiz ing properties of the softener.

Example IV A butadiene-styrene copolymer shoe upper stock composition was prepared as follows, in which acid soluble oil was the softener employed.

' Parts by weight Butadiene-styrene copolymer 1 Bonzothiazyldisulfide. I An ester of two molecules of dlphenyl guanldine and one molecule phthalic acid.

A commercial factory control stock was evaluated for comparison. Stress-strain properties lyst comprising hydrofluoric acid and therein reacting said isoparafiin with said olefin at a temperature inthe range of 50 to 150 F. to form alkylate, separatin efiluent from said alkylation zone into a hydrocarbon phase containing alkylate and a hydrofluoric acid phase containwere measured at F. and are as follows: 40 ing impurities comprising water, organic fluorine Stress, p. s. i.

Minutes Per Cent Softener Cure Per Cent Elongation Eloncation 267 F. at Break at Break UNAGED 2 2 30 Am Soluble 32 238 hit 2338 $33 332 45 330 820 1,235 1, 520 1, 610 450 75 350 900 1, 365 1,025 1,040 405 OVEN AGED 24 HRS. 212).

Acid Soluble {it 5i 5:155 538 $3? 45 850 1, s20 1,785 225 products of good compounds and a lay-product oil, recovering alkylate from said hydrocarbon phase; recovering said acid-soluble oil from said acid phase by removing said hydrofluoric acid phase from the zone of said separating and heating same to a temperature in the range of 250 to 350 F. and passing acid phase thus heated to a flash distillation zone and therein separating hydrofluoric acid and water as an overhead flash distillation product, passing residual oil product from said flash distillation zone to a fractionation zone wherein a kettle temperature of about 400 F. is employed, in said fractionation zone decomposing organic compounds and recovering same as overhead fractionation product together with any free hydrofluoric acid and water not removed from said flash distillation above described, recovering oil kettle product free of water, hydrofluoric acid and organic fluorine compounds from said fractionation zone; said oil kettle product being said acid-soluble oil and having an API gravity at 60 F. in the range of to 30, a viscosity at 100 F. in the range of 100 to 1000 SUS, a, flash point in the range of 190 to 250 F., a fire point in the range of 220 to 270 F., a pour point at a temperature in the range of 30 to 5, a total solids content in the range of 65 to 80 per cent by weight, an iodine number within the limits of 150 to 300 and an aniline point within the range of 30 to 100.

2. As a new composition of matter, a rubbery copolymer of 1,3-butadiene and styrene, com-i pounded with from 8 to 40 weight per cent of an acid-soluble 011, said acid-soluble oil having an API gravity at 60 F. in the range of 10 to 30, a viscosity at 100 F. in the range of 100 to 1000 SUS, a flash point in the range of 190 to 250 F.,

.a, fire point in the range of 220 to 270 a pour point at a temperature in the range of 30 to 5, a total solids content in the range of 65 to 80 per cent by weight, an iodine number within the limits of 150 to 300 and an aniline point within the range of 30 to 100, and produced by reacting a hydrocarbon stock in the presence of a catalyst comprising hydrofluoric acid, separating from a resulting reaction mixture 2. hydrocarbon phase containing a hydrocarbon reaction product, and a hydrofluoric acid phase containing impurities comprising an oil and organic fluorine compounds, flash distilling said hydrofluoric acid phase to remove hydrofluoric acid therefrom as an overhead flash distillation product, fractionating residual flash distillation product and concomitantly decomposing organic fluorine compounds and removing decomposition products thus formed as overhead fractionation product, recovering a kettle product from said fractionation free of hydrofluoric acid and organic fluorine compounds, said kettle product being said acid soluble oil:

3. As a new composition of matter, a rubbery copolymer of 1,3-butadiene and styrene, compounded with from 8 to weight per cent of an acid-soluble oil, said acid-soluble oil having an API gravity at F. in the range of 10 to 30, a viscosity at 100 F. in the range of 100 to 1000 SUS, a flash point in the range of 190 to 250 F., a fire point in the range of 220 to 270 F., a pour point at a temperature in the range of 30 to 5, a total solids content in the range of to per cent by weight, an iodine number within the limits of to 300 and an aniline point within the range of 30 to 100, and produced by reacting a hydrocarbon stock in the presence of a catalyst comprising hydrofluoric acid, separating from a resulting reaction mixture a hydrocarbon phase containin a hydrocarbon reaction product, and a hydrofluoric acid phase containing oil-soluble impurities, flash distilling said hydrofluoric acid phase to remove hydrofluoric acid therefrom as an overhead flash distillation product, recovering a kettle product from said flash distilling free of hydrofluoric acid, said kettle product being said acid soluble oil.

4, A composition in accordance with claim 3 wherein said acid soluble oil is a resinous residual fraction recovered from said kettle product by removal of light constituents by vacuum distillation, said residual fraction comprising from 15 to 40 per cent of said kettle product and distilling in the range of 390 to 600 F. at a pressure of 10 mm. of Hg, having an iodine number in the range of to 160, having a softening point in the range of 110 to F., and having an acidity of less than 0.3.

LAWRENCE R. SPERBERG. CHESTER C. CRAWFORD.

REFERENCES CITED The following references are of record in, the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,523,926 September 26, 1950 LAWRENCE R. SPERBERG ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 14, for the Word is read in; column 8, line 67, for said read acid and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice.

I I Signed and sealed this 19th day of December, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents. 

3. AS A NEW COMPOSITION OF MATTER, A RUBBERY COPOLYMER OF 1,3-BUTADIENE AND STYRENE, COMPOUNDED WITH FROM 8 TO 40 WEIGHT PER CENT OF AN ACID-SOLUBLE OIL, SAID ACID-SOLUBLE OIL HAVING AN API GRAVITY AT 60*F. IN THE RANGE OF 10 TO 30, A VISCOSITY AT 100*F. IN THE RANGE OF 100 TO 1000 SUS, A FLASH POINT IN THE RANGE OF 190 TO 250*F., A FIRE POINT IN THE RANGE OF 220 TO 270*F., A POUR POINT AT A TEMPERATURE IN THE RANGE OF -30 TO 5, A TOTAL SOLIDS CONTENT IN THE RANGE OF 65 TO 0 PER CENT BY WEIGHT AN IODINE NUMBER WITHIN THE LIMITS OF 150 TO 300 AND AN ANILINE POINT WITHIN THE RANGE OF 30 TO 100, AND PRODUCED BY REACTING A HYDROCARBON STOCK IN THE PRESENCE OF A CATALYST COMPRISING HYDROFLUORIC ACID, SEPARATING FROM A RESULTING REACTION MIXTURE A HYDROCARBON PHASE CONTAINING A HYDROCARBON REACTION PRODUCT, AND A HYDROFLUORIC ACID PHASE CONTAINING OIL-SOLUBLE IMPURITIES, FLASH DISTILLING SAID HYDROFLUORIC ACID PHASE TO REMOVE HYDROFLUROIC ACID THEREFROM AS AN OVERHEAD FLASH DISTILLATION PRODUCT, RECOVERING A KETTLE PRODUCT FROM SAID FLASH DISTILLING FREE OF HYDROFLUORIC ACID, SAID KETTLE PRODUCT BEING SAID ACID SOLUBLE OIL. 